This invention relates to a process for separating solids from dust-containing high-boiling hydrocarbons.
The thermal treatment of bituminous or oil-containing materials, such as hard coal, brown coal, tar sands, oil shale or the like involves a condensation of the hydrocarbon-containing products with formation of a dust-enriched high-boiling fraction. Similar products result from the thermal or catalytic cracking of hydrocarbons. Dust-enriched tar becomes available also in the pressure gasification of coal.
German Pat. No. 1,909,263 discloses a dry distillation process in which dust-enriched heavy oil is diluted and then filtered so that the liquid phase is separated as completely as possible from the solids. The filtered liquid phase is then separated by distillation into heavy oil and diluent, and the latter is re-used. To dry the filter cake, the same is mixed with hot dry distillation residue and is thus heated. As a result, residual diluent is evaporated. The evaporated diluent is condensed and also returned into the separating process. This single-stage process is relatively expensive, particularly when the heavy oil has a high dust content and when high throughput rates are desired.